Optical properties of nanostructured carbon and gold nanoparticle hybrids

ABSTRACTWe report simulation of optical properties of hybrid geometry comprised of multilayer graphene shell encapsulated gold nanoparticles loaded with carbon nanotubes. The discrete dipole approximation (DDA) method was employed. The results indicated that the optical properties of encapsulated gold nanoparticles were not suppressed by the carbon material coating. Furthermore, low scattering effects were also observed. The simulation method helped visualize the near-surface normalized electric field, which is directly related to the intensity of hot spots on the surface of these hybrid nanoarchitectures.

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Fabrication of SERS Active Substrates by Nanoimprint Lithography

MRS Proceedings ◽

10.1557/proc-1054-ff01-03 ◽

2007 ◽

Vol 1054 ◽

Author(s):

Kebin Li ◽

Bo Cui ◽

Liviu Clime ◽

Teodor Veres

Keyword(s):

Numerical Simulations ◽

Hot Spots ◽

Nanoimprint Lithography ◽

Rhodamine 6G ◽

Low Cost ◽

Dipole Approximation ◽

Sers Substrates ◽

The Given ◽

Method Show ◽

Dda Method

ABSTRACTA method for low-cost fabrication of SERS substrates in rapid and reproducible way based on nanoimprint lithography (NIL) method has been developed. The SERS enhancement for detection of Rhodamine 6G molecules is demonstrated on two model nanostructures comprising either Au nano-crescents or Ag nano-wells fabricated by this method. Numerical simulations based on discrete dipole approximation (DDA) method show that the observed enhancement of the SERS signal for the given geometries originates in hot-spots localized at the tips of the nanocrescent. For the nanowell, the hotspots are mainly localized inside the cavity, on the side of the nanodonut, or at the edge of the bottom nanodisc when it is excited by a laser at the wavelength of 785 nm.

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Accuracy of the discrete dipole approximation for simulation of optical properties of gold nanoparticles

Journal of Nanophotonics ◽

10.1117/1.3335329 ◽

2010 ◽

Vol 4 (1) ◽

pp. 041585 ◽

Cited By ~ 41

Author(s):

David De Kanter

Keyword(s):

Gold Nanoparticles ◽

Optical Properties ◽

Dipole Approximation ◽

Discrete Dipole Approximation

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Alkanethiol Mediated Release of Surface Bound Nanoparticles Fabricated by Nanosphere Lithography

MRS Proceedings ◽

10.1557/proc-0900-o13-08 ◽

2005 ◽

Vol 900 ◽

Cited By ~ 2

Author(s):

Jing Zhao ◽

Amanda J Haes ◽

Xiaoyu Zhang ◽

Shengli Zou ◽

Erin M Hicks ◽

...

Keyword(s):

Optical Properties ◽

Ag Nanoparticles ◽

Theoretical Calculations ◽

Nanosphere Lithography ◽

Dipole Approximation ◽

Force Microscopy ◽

Atomic Force ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Dda Method

ABSTRACTThis work presents an innovative approach to produce monodisperse solution-phase triangular silver nanoparticles with well-controlled geometry. Ag nanotriangles are fabricated by nanosphere lithography (NSL), functionalized with alkanethiol molecules and then released from the substrate into solution. The resulting single isolated nanoparticles are subsequently asymmetrically functionalized with alkanedithiol molecules to form dimer pairs. The optical properties of the Ag nanoparticles have been measured using UV-Vis spectroscopy while their structural properties have been characterized using atomic force microscopy (AFM) and transmission electron microscopy (TEM). Theoretical calculations based on Mie theory and the Discrete Dipole Approximation (DDA) method have been done to interpret the optical properties of the released Ag nanoparticles.

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Linear Optical properties of 2D assembly of interacting gold nanoparticles: Analytical approach in dipole approximation

Physica Scripta ◽

10.1088/1402-4896/ac2da5 ◽

2021 ◽

Author(s):

Asef Kheirandish ◽

Nasser Sepehri Javan ◽

Afsoon Farhoomand ◽

Roshanak Etemadpour

Keyword(s):

Gold Nanoparticles ◽

Optical Properties ◽

Analytical Approach ◽

Dipole Approximation ◽

Linear Optical Properties ◽

Linear Optical

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Growth of silicon nanowires-based heterostructures and their plasmonic modeling

MRS Proceedings ◽

10.1557/opl.2013.542 ◽

2013 ◽

Vol 1547 ◽

pp. 103-108 ◽

Cited By ~ 5

Author(s):

Yuan Li ◽

Wenwu Shi ◽

John C. Dykes ◽

Nitin Chopra

Keyword(s):

Gold Nanoparticles ◽

Optical Properties ◽

Wave Vector ◽

Incident Wave ◽

Silicon Nanowires ◽

Axial Direction ◽

Dipole Approximation ◽

Extinction Efficiency ◽

Spatially Resolved ◽

Incident Wave Vector

ABSTRACTComplex nanoscale architectures based on gold nanoparticles (AuNPs) can result in spatially-resolved plasmonics. Herein, we demonstrate the growth of silicon nanowires (SiNWs), heterostructures of SiNWs decorated with AuNPs, and SiNWs decorated with graphene shells encapsulated gold nanoparticles (GNPs). The fabrication approach combined CVD growth of nanowires and graphene with direct nucleation of AuNPs. The plasmonic or optical properties of SiNWs and their complex heterostructures were simulated using discrete dipole approximation method. Extinction efficiency spectra peak for SiNW significantly red-shifted (from 512 nm to 597 nm or 674 nm) after decoration with AuNPs, irrespective of the incident wave vector. Finally, SiNW decorated with GNPs resulted in incident wave vector-dependent extinction efficiency peak. For this case, wave vector aligned with the nanowire axial direction showed a broad peak at ∼535 nm. However, significant scattering and no peak was observed when aligned in radial direction of the SiNWs. Such spatially-resolved and tunable plasmonic or optical properties of nanoscale heterostructures hold strong potential for optical sensor and devices.

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Aggregation affects optical properties and photothermal heating of gold nanospheres

Scientific Reports ◽

10.1038/s41598-020-79393-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yiru Wang ◽

Zhe Gao ◽

Zonghu Han ◽

Yilin Liu ◽

Huan Yang ◽

...

Keyword(s):

Optical Properties ◽

Cross Section ◽

Laser Heating ◽

Dipole Approximation ◽

Gold Nanospheres ◽

Extinction Cross Section ◽

Heating Efficiency ◽

Photothermal Heating ◽

New Framework ◽

Laser Calorimetry

AbstractLaser heating of gold nanospheres (GNS) is increasingly prevalent in biomedical applications due to tunable optical properties that determine heating efficiency. Although many geometric parameters (i.e. size, morphology) can affect optical properties of individual GNS and their heating, no specific studies of how GNS aggregation affects heating have been carried out. We posit here that aggregation, which can occur within some biological systems, will significantly impact the optical and therefore heating properties of GNS. To address this, we employed discrete dipole approximation (DDA) simulations, Ultraviolet–Visible spectroscopy (UV–Vis) and laser calorimetry on GNS primary particles with diameters (5, 16, 30 nm) and their aggregates that contain 2 to 30 GNS particles. DDA shows that aggregation can reduce the extinction cross-section on a per particle basis by 17–28%. Experimental measurement by UV–Vis and laser calorimetry on aggregates also show up to a 25% reduction in extinction coefficient and significantly lower heating (~ 10%) compared to dispersed GNS. In addition, comparison of select aggregates shows even larger extinction cross section drops in sparse vs. dense aggregates. This work shows that GNS aggregation can change optical properties and reduce heating and provides a new framework for exploring this effect during laser heating of nanomaterial solutions.

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